Piston



P. M. FREER PISTON Nov. 4, 1930.

Filed June 1'7 1929 PPM/k5 ATTORN EYS Patented Nov. 4, 1930 PATENTOFFICE PHELPS M. FREEZE, OF DETROIT, MICHIGAN rIsroN Application filedJune 17, 1929. Serial NO. 371,577.

The invention relates to pistons and refers more particularly to pistonshaving separately formed heads and skirts. One of the objects of theinvention is to provide an improved construction of piston in which thehead and skirt are automatically centered relative to each other.Another object is to provide an improved device for securing the headand skirt together. Further objects of the invention reside in the novelfeatures of construction and combinations and arrangements of parts aswill be more fully hereinafter set forth.

In the drawings: Figure 1 is an elevation, partly in section, of apiston embodying my invention, Figures 2 and'3 are cross sectionsrespectively on lines 22 and 33 of Figure 1;

Figure t is an elevation of a portion of the securingdevice beforeassembly in the piston;

Figure 5 is a section through a piston having a modified device forsecuring the head and skirt together; Figure 6 is an elevation themodified securing device.

of a portion of In general, the piston comprises thehead 1 I and theskirt 2; The head is preferably formed of aluminum or an aluminum alloyand the skirt is preferably'formed of iron, the latter being adapted forengagement with the wall of the cylinder in which the piston operatesand the former being preferably out of engagement with the wall of thecylinder. The head has the annular grooves 3 for receiving the pistonrings and the pair oi diametrically opposite hubs i for receiving thewrist-pin which connects the connecting rod to the piston. The head hasthe annular skirt engaging shoulderno and the annular outwardlyextending flange 6 providing the annular shoulder 7 opposed to theannular shoulder 5. The skirt surrounds the lower portion of the headincluding the hubs and the outwardlyextending annular jflange and isspaced laterally therefrom and one end of thisskirt is adapted to engagethe annular shoulder 5.

. For the purpose of automatically center- 59 Y ing the-head andskirtrelat-ive to'each other 1 the annular shoulder 5 and the abuttingend of the skirt are correspondingly bevelled.

For securing the head and skirt together I have provided as shown inFigures 1 to 4 inclusive, the resilient wire 8 which abuts the annularshoulder 7 and the inwardly extending flange 9 upon the end of the skirtabutting the annular shoulder 5. This resilient wire is loopedand curvedto present an annulus and the loops are inclined so that the annulus isfrusto-conical. The loops, in general, extend longitudinally of thepiston but are inclined outwardly from their bases. Each loop has thelegs 10 and 11 which are inclined peripherally relative to the base ofthe loops, the cam 12 connecting into the leg 10 and the extension 13connecting into the cam 12 and the leg 11. The

, angle of inclination of each leg 11 is preferably less than the angleof inclination of each leg 10. The inwardly extending flange 9 isinterrupted to provide recesses 14. for engaging the extensions 13 andintermediate solid portions 15 forming shoulders at one end for engagingthe annular shoulder 5 and at the other end for engaging the cams 12.

The wire may be formed either continuous as by welding its ends or maybe formed as shown with transverse terminals 15' extending within.transverse bores 16 in the head. securing the terminals in the bores,there is thescrew 17 threaded into the lower portion of the head 1 andhaving its head overlapping the base of thewire adjacent the terminals.

This screw also functions to hold the wire against the annular shoulder7. In addition to this screw, therepreferably are one or more similarscrews spaced angularly around the head and overlapping the base of thewire for holding the wire against the annular shoul der 7. r

To assemble the parts the wire is first placed around the lower portionof'the head l' andits terminals 15 are inserted in the bores 16 of thehead placing the wire under tension after which the screws 17 aresecured in place. The skirt 2 is then telescoped over the lower portionof the'head with the solid portions of the annular flange 9 upon thisskirt in line with the extensions 13 of thewire and -forcing the sameinwardly. After the skirt has been completely telescoped over the lowerportion of the head so that it abuts the annular shoulder 5 upon thehead, the skirt is then rotated to engage the shoulders formed by thesolid portions of the annular flange 9 with the lowermost portions ofthe cams 12. Upon continued rotation of the skirt, these shoulders rideup on the c ms and the skirt is firmly engaged with the annular shoulder5 of the head, at which time the shoulders i'ornr'edby the recesses i lof the annular flange 9 embrace the extensions 13 and hold the skirtfrom rotation in either direction. These shoulders are preferablybevelled to converge radially outward to take care of the variations indimensions of the extensions and recesees and at the same time insurelocking against rotation. I

When the loops of the wireare ini'iorn'ial position before assembly ofthe wire in the piston, as shown in Figure t, the lengths of the legs 10and 11 of the wire, are so great that after assembly of the parts of thepiston and when the skirt is being rotated and consequently cammed intoplace, the legs are periphally inclined to agreater extent and the wireis as a result placed under increased compression. V

IVith this construction, it will be seen that I have provided aconstruction of piston which has its head and skirt automaticallycentered, both by reason of the bevelled interengaging faces upon thehead and skirt and the frusto-conical wire under compression bothradially and axially oi the piston. It will also be seen that the wiremay be mounted on the head under tension and that this wire is undercompressionboth radially and axial- 1y when it locks the head and skirttogether. Furthermore, the wire is of cheap construction,-and can beuniformly spring tempered owing to uniform cross section and no cross orshort grain. It will additionally be seen that the wirepermits variationin expansion of the head-and skirt.

In the modification shown in Figs. 5 and (5 the skirt 18 has theinwardly extending annular flange 18 at its end abutting the annularshoulder 19 upon the head 20. This inwardly extending flange is bevelledat 21 to engage the upper ends of the loops of the resilient looped wire22 which, as shown, is con tinuous and is preferably secured to the headby one or morescrews similar to those for securing the wire 8 to thehead 1.

IVhat I claim as my invention is:

1. In a piston, the combination with head and skirt members, of meansfor securing said =j head. and skirt members together, including awire,said means-associated with said wire and one of said head and sk rtmembers for establishing a cam engagement therebetween upon relativerotation of said last mentionedf member. and said Vii-6..

2. In a piston, the combination with head and skirt members, of meansfor securing said head and skirt members together, including a wiresecured to one of said head and skirt members and means associated withsaid wire and the other of said head and skirt members for establishinga cam engagement therebetweei'i upon relative rotation of said lastmentioned member and wire.

3. In a piston, the combination with head and skirt members-of a wiremember secured to one of said head and skirt members and meansassociated with said wire member and the other of said head and skirtmembers for establishing a we'dgin action therebetween to secure saidhead and skirt members together.

4. In a piston, the combination with head and skirt members, of meansfor securing said head and skirt members together including a wiremember having. a cam portion -en gaging one of said head and skirtmembers upon relative rotation of said last mentioned member and wiremember, and means for holding said wire member in cam engagement withsaid last mentioned member.

5. In a piston, the combination with head and skirt members, of a wirering secured to one of said members and having a cam portion engagingwith the other upon relative rotation of said last mentioned member" andwire ring and means for holding said wire ring in cam engagement withsaid last mentioned member. 7

6. In a piston, the combination with head and skirt members, of meansfor securing said head and skirt members together including a wiremember having a cam portion engaging with one of said head and skirtmember's upon relative rotation of said lastmentioned member and wiremember, said last mentioned member and wire member-having cooperatinginterlocking portions for holding said wire member in cam engagementwith said last mentioned member.

7 In a piston, the combination with head and skirt members, of means forsecuring said head and skirt members together, including a resilientlooped wire members engaging one of said head and skirt members andmeans associated with said wire member and the other of said head andskirt members for establishing a wedging action therebetween.

8. In a piston, the combination with a head member having a shoulder anda skirt member abutting said shoulder and having an inwardlyextending'flange, of means for securing said head member and skirtmember to each other including a resilient looped wire member abuttingsaid head member, and the inwardly extending flange of said skirt: m mher, said inwardly extending flangeand-a loop of said wire Inemberhavingcooperatifig interlocking shoulders for holding said skirt member fromrotation relative to said Wire member. 7

9. In a piston, the combmatlon with a head member having a shoulder andan out- Wardly extending flange, and a skirt member having an inwardlyextending flange abutting said shoulder, of means for securing said headmember and skirt member to each other including a resilient looped wiremember engaging said outwardly extending flange and having its loopsprovided with cam portions for engaging said inwardly extending flangeand with extensions beyond said cam portions, said inwardly extendingflange being interrupted to provide recesses for receiving saidextensions.

In testimony whereof I aflix my signature.

' PHELPS M. FREER.

